Electric heater.



No. 735,798. PATENTED AUG. 11, 1903. J. F. MoELROY.

ELECTRIC HEATER.

APPLICATION FILED APR. so, 1903.

no MODEL.

UNITED STATES rammed August 11, 1903.

JAMES F. MCELROY, ALBANY, NEW YORK.-

ELECTRIC HEATER.

SPECIFICATION forming part of Letters Patent No. 735,798, dated August11, 1903. Application filed April 30, 1903. Serial No. 154,923. (Nomodel.)

To all whom it may concern:

Be it known that 1, JAMES F. MCELROY, a citizen of the United States,residing at Albany, county of Albany, and State of New York, haveinvented certain new and useful Improvements in Electric Heaters, ofwhich the following specification, with its accompanying drawings, setsforth as an illustration that form of my invention which I now considerthe best one out of the various forms in which the principles of theinvention may be embodied.

In the drawings, Figure 1 shows the con struction of the heater, andFig. 2 shows a diagram of the circuits for which my device is intended.

It has heretofore been customary in electric heating to provide a seriesof heaters and to divide each heater of the series into sections,

which sections are respectively included in separate circuits, so thateither all or a part of each heater of the series may be energized,according as all or a part of the said separate circuits, each includingsections of different heaters, are connected to the source of supply.Usually two circuits are employed and the sections in one circuit madeup of finer wire than that used in the other section, so as to have asmallerheating capacity. Then the circuit with the fine-wire sectionswill give the lowest degree of heat when it alone is connected up. Thesecond circuit, with heatersections of larger Wire, will when used alonegive a second degree of heat, and both circuits used together will givea third degree.

Heretofore these different sections of a heater: coil have been placedside by side on a con' tinuous supporting-core, each occupying the samelongitudinal space on the core; but this gives rise to an unevendistribution of heat, since the ilarge coil, giving about twice the heatof the smaller coil, occupies an equal length of the core, with theresult that the heat per unit of length is twice as intense along onehalf of the core as it is along the other half. I have therefore soarranged the respective coils that the distribution of heat along thecore will be uniform and have, the same intensity per unit of length atall points, whether measured along the smaller or along the largersection of heating-coil.

This I accomplish by so disposing the coils on the core that each shalloccupy a portion of thelongitudinal space correspondingapproximately tothe fraction of the total heat represented by it. Thus of two coils, onehaving half the heatintensity of the other, the smaller will occupy one-third and the larger twothirds of the length of the core.

In the drawings, coils A and B represent sections of a unitaryheating-coil placed side by side on a core or support 0, the coil Abeing of fine wire and the coil B of coarse wire. Each coil is connectedin a circuit containing corresponding coils in other similar heaters. asshown in 2. The switch D of Fig. 2 will in its first position connect tothe source of supply the circuit containing all the sections A, whichwill give the lowest degree of heat, and in its next position willconnect to the source of supply the circuit containing all the coils B,which will double the heat, assuming that each coil B gives twice theheat intensity of each coil A. In its third position the switch willconnect in both circuits, which will treble the intensity of heat. Itwill be observed, however, that the coil A occupies but one-third of thelongitudinal space on the core 0, and the coil B two-thirds, so thatwhen both coils are energized the heat intensity per unit of length ofthe heater will be uniform from end to end, whether measured along coil.A or coil B.

This will provide the uniformity of heat distribution in the oneapparatus, which I seek to attain.

What I claim as new, and desire to secure by Letters Patent, is-

1. An electric heater havingits heating-coil divided into sections ofdifferent intensity each section occupying a longitudinal spacesubstantially proportionate to its fraction of the total heat intensity.

2. An electric heater having its heating-coil divided into sections ofdifferent intensity located in line along the length of the heater andeach section occupying a longitudinal space substantially proportionateto its frac tion'ot' the total heat intensity.

3. An electric heater havingits heating-coil wound on a continuous coreand divided into sections of dilterent intensity each section occupyinga space on the core substantially proportionate to its fraction of thetotal heat 7 tionate to its fraction of the total heat intenintensity.sity of the heater.

4. A series of electric heaters, each having In witness whereof I havehereunto set my its heating-coil divided into sections of difierhand,before two subscribing witnesses, this 5 cut intensity, all the coils ofequal intensity 28th day of April, 1903.

being included in a single circuit extending T a through all the heatersand each section 00- JAMES MCELROX' cupying a space in its heaterlongitudinally Witnesses:

in line with the other sections of the same BEULAH CABLE,

IO heater and of a length substantially propor- ERNEST D. JANSEN.

